Figure 1.

Causal diagrams going from Plasmodium spp. infection to severe malaria through parasitemia and clinical attack. A. Two possible pathways going from infection to parasitemia, via IgG-mediated acquired immunity or directly from infection to parasitemia, and multiple possible pathways for the impact of genetic polymorphism on IgG, parasitemia, clinical attack or severe malaria. B. An example specifying Plasmodium falciparum as the infective species, and the influence of genetic polyporphism at FcγRIIa distinguishing between FcγRIIa homozygotes for H131 vs. heterozygotes & homozygotes for R131 (recessive model) acting on parasitemia via IgG2 levels. The causal diagrams were created using DAGittyv.2.0 (http://www.dagitty.net/).